The sodium salt of (S)-2-(6-methoxy-2-naphthyl)propionic acid is a commercially available anti-inflammatory agent with the generic name of naproxen sodium.
A process used for the production of naproxen sodium involves reacting (S)-2-(6-methoxy-2-naphthyl)propionic acid dissolved in toluene with an aqueous sodium hydroxide solution, with subsequent removal of water by heating the slurry to an ending temperature of 100.degree. C. and a pressure of 1 atmosphere. The resultant anhydrous naproxen sodium has an average particle size in the range of about 30 to about 70 microns, and is in the form of small needle-like particles typically having an aspect ratio of about 10, with the length being approximately 200 to 300 microns and the width ranging from about 15 to about 45 microns. To achieve the required high chiral purity naproxen sodium (99% minimum), it has been necessary to use long cycle times and to form and use (S)-2-(6-methoxy-2-naphthyl)propionic acid of relatively high chiral purity (97% minimum).
A highly desirable contribution to the art would be the provision of forms of sodium (S)-2-(6-methoxy-2-naphthyl)propionate having an average particle size significantly larger than about 70 microns, especially if such material could have a chiral purity of at least 98% (S)-enantiomer, and a process technology enabling the production of such material. The achievement of these objectives would be of inestimable value from the standpoints, inter alia, of processing time, plant capacity and product handling operations.
This invention is deemed to constitute such a contribution to the art, as it enables the achievement of the foregoing objectives.